Significant improvement of machinability of Cf/SiC composites through matching laser scanning spacing and abrasive belt grain size

To improve the application and service of Cf/SiC composites as advanced high-temperature structural materials, it is critical to achieve their high-efficiency and low-damage machining. In this study, the laser-ablating assisted grinding (LAAG) method was presented, and the connection of damage behavior and removal mechanism with laser and grinding processes was revealed. The results demonstrated that the surface of Cf/SiC composites after laser ablation was covered with a substantial number of loose oxides primarily composed of SiO2. Laser ablating process, grinding parameter and abrasive belt selection have a significant impact on the machining results. By fabricating an ablative layer with small laser scanning spacing, and selecting small abrasive grains and feed rate during grinding, the machinability was improved and a relatively lower-damage grinding surface could be obtained. Under the optimal combination of process parameters, the grinding force and temperature of LAAG could be reduced by up to 85% and 35%, respectively. In this case, the subsurface damage of Cf/SiC composites occurred only in the form of microcracks rather large-scale fracture, and the formation of interface debonding and matrix cracking was significantly reduced. Furthermore, the grinding chips were mostly shown as micron-sized powders, indicating that the removal mechanism of Cf/SiC composites was primarily the micro-fractured and attrition wear of laser-ablated layer.